Originally Posted by dddd

This is all kinds of good news since I have tended to remove triple gruppos from many of my used-bike purchases, so have the parts already.
Especially since the double rear derailers fetch such a premium and seem to just about never come into the co-ops as donations.

I might do a similar setup using a 13-30 HG cassette, but 13-34t would be incredible. I have used an 11-34t cassette with an Ultegra 9s RD but it does shift with a clunk up to the largest cog.
I've found the ratio gaps on the 13-34t to be the biggest I can go without it becoming a real performance issue.
SRAM offers 7s cassettes these days that are much lighter, have a much nicer finish and with slightly different ratio staging, so are another excellent option here.

Depending on the chainring size difference, the chain gap might fall out of the range that the B-tension screw can fully accomodate, though of course the long cage gives it the best chance of working well.

Shimano 7s cog spacing is about the same as Campag 8s, but note that the 2-3 cog spacer (between 2nd and 3rd-smallest cogs) is 3.3mm instead of 3.1mm like the rest of the plastic spacers. The 3.3mm spacer has a darker color. It can be replaced with a 3.1mm spacer if there is any indication that this would help with the indexing.

Lastly, there are now eight ShiftMate adapters available for mixing and matching campag and Shimano parts (even for the new Campag 12s shifters, so you could literally run a 10-51t cassette with Ergolevers if you buy the right parts).